When information needs to be communicated in a secure manner one typically turns to cryptographic techniques. It is generally recognized that with many cryptographic techniques the encrypted data can be recovered by an adversary, but only if the adversary has sufficient resources (e.g., computing power) and sufficient time. Most users are satisfied when a method is secure “enough,” meaning that the time, effort, or expense to recover the data embedded in an encrypted message is too great to make the data useful to an adversary.
With the above in mind, cryptographic techniques usually depend on encryption and decryption keys being in possession of the communicating parties. Aside from the concern about the inherent security of message encrypted with a particular method, the biggest concern is with the secure creation, distribution and maintenance of the keys.